Ls3 Ported oil pump, what oil??
12-20-2016, 09:46 PM
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Ls3 Ported oil pump, what oil??
I have a ls3 with a .600 lift cam, ported heads, ls7 lifters/rockers, and a ported oil pump. The oil pressure is pretty low, and it has 5w 20 in it right now... (my dumbass didn't read the container before I poured it in... stupid mistake.) What oil would be best for this application? It's usually hot here in Arizona. I was thinking 10w 30.
12-21-2016, 01:33 AM
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12-21-2016, 08:23 AM
#4
Drifting
I can’t comment from a position of knowledge about the impact of your mods, but that said, it’s hard for me to imagine any scenario where you are better off with 10W30 than 5W30. The W number gives you an indication of viscosity at startup temperature, while the upper number refers to viscosity at running temperature. All oil is too thick at startup temperature, but 5W30 is less bad than 10W30 in that regard. Actual viscosity numbers (as opposed to the general indicators of numbers like 5W30) are as follows. When hot at 212F, viscosity of both grades is about 12 centistokes. At 90F, 10W30 is about 90 centistokes while 5W30 is about 60. At 60F those numbers are about 170 versus 100. At 32F, the numbers are about 370 versus 190. Any time you are above about 100 centistokes, it is potentially a very high wear zone.
The only conditions under which you might be better off with a higher W number would be if the mods in your engine required a heavier oil at running temperature, such as 40 or 50 weight. Even there, a higher W number like 10W40 or 15W50 makes things worse at startup temperature. The advantage of a higher W number as you go higher in the plain number is that the wider the spread between the W number and plain number, the more VI improver additive you need. With a full synthetic, you can make a 25 spread (like 5W30 or 15W40) without much, if any VI improver. But higher spreads (like the 35 spread of 5W40 or 15W50) require VI improver. The disadvantage of VI improver is that it can degrade, and if it degrades, you lose viscosity on the high end, leaving your oil too thin at running temperature.
The only conditions under which you might be better off with a higher W number would be if the mods in your engine required a heavier oil at running temperature, such as 40 or 50 weight. Even there, a higher W number like 10W40 or 15W50 makes things worse at startup temperature. The advantage of a higher W number as you go higher in the plain number is that the wider the spread between the W number and plain number, the more VI improver additive you need. With a full synthetic, you can make a 25 spread (like 5W30 or 15W40) without much, if any VI improver. But higher spreads (like the 35 spread of 5W40 or 15W50) require VI improver. The disadvantage of VI improver is that it can degrade, and if it degrades, you lose viscosity on the high end, leaving your oil too thin at running temperature.
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WoodinvilleDan (08-30-2023)
12-21-2016, 10:08 AM
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Melting Slicks
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Very interesting info LDB. I have a forged 402ci with a high volume oil pump. My builder recommended 10w30 and even suggested 15w50 in the hot summer months. I wasn't sure about the 15w50 and discussed it with Amsoil, who recommended their Zrod 10w30 for the added ZDDP protection and told me to keep an eye on the oil temps and pressure. I haven't pushed the engine too hard yet but I have seen oil temps in the 230°-240°. This was on the shop's 10w30 after break in, not sure on the brand. I recently put in the Zrod but it's winter now in the north east so I'll have to wait until summer to check oil temps when the weather is 90℉+ and humid. I don't know how comfortable I am with such a large spread of the 15w50 and I certainly don't want to change oil just to run the car for the 3-4 months of summer heat. I know more power can mean more heat but I was hoping for a safe all around viscosity. Your thoughts?
Last edited by 5knives; 12-21-2016 at 11:08 AM.
12-21-2016, 10:18 AM
#6
Melting Slicks
** First call your engine builder and see what they suggest.
12-21-2016, 12:21 PM
#7
Drifting
Very interesting info LDB. I have a forged 402ci with a high volume oil pump. My builder recommended 10w30 and even suggested 15w50 in the hot summer months. I wasn't sure about the 15w50 and discussed it with Amsoil, who recommended their Zrod 10w30 for the added ZDDP protection and told me to keep an eye on the oil temps and pressure. I haven't pushed the engine too hard yet but I have seen oil temps in the 230°-240°. This was on the shop's 10w30 after break in, not sure on the brand. I recently put in the Zrod but it's winter now in the north east so I'll have to wait until summer to check oil temps when the weather is 90℉+ and humid. I don't know how comfortable I am with such a large spread of the 15w50 and I certainly don't want to change oil just to run the car for the 3-4 months of summer heat. I know more power can mean more heat but I was hoping for a safe all around viscosity. Your thoughts?
The problem with 15W50 is that if you drive on the street very much, starting from cold, you’re going to spend a fair amount of time over 100 centistokes during warmup. Quite a few people make 5W40, which is a decent compromise if you spend a lot of time at or over 260F and don’t want to worry about cold start issues. It does have a 35 spread, so uses some VI improver, but those additives are getting more stable, so aren’t as risky as they used to be. I’d be a bit nervous leaving it in too much over 5000 miles, but I’ve been retired 6 years so haven’t seen any VI improver stability data since then. Some of the European makes like BMW recommend 5W40 for normal change intervals, and you wouldn’t think they’d do that unless they had seen stability data to support it.
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mikeCsix (12-21-2016)
12-21-2016, 01:10 PM
#8
Burning Brakes
Typically break in oils are straight 30 weight. I would replace the oil with a 5w-30 ester based oil and see what happens. If it still shows low (under 35psi - hot idle) then you likely have a problem. What lifters are you running?
** First call your engine builder and see what they suggest.
** First call your engine builder and see what they suggest.
Edit; If the mods make the OM irrelevant, I stand corrected.
Last edited by Batman75; 12-21-2016 at 01:33 PM.
12-21-2016, 01:42 PM
#9
Le Mans Master
Below 35 PSI at hot idle is a problem??? You must think the Owners Manual doesn't know what it's talking about. Normal oil pressure is between 20 and 80 PSI. The low oil pressure warning doesn't come on above 5 PSI.
Edit; If the mods make the OM irrelevant, I stand corrected.
Edit; If the mods make the OM irrelevant, I stand corrected.
there are alot of LS motors out there with oil pressure of 25 to 30 lbs at hot idle which is considered to be normal....My LS2 has 26 lbs at hot idle and that is four times what GM lists as the minimum...WW
Last edited by WW7; 12-21-2016 at 03:29 PM.
12-21-2016, 03:26 PM
#10
Melting Slicks
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I can’t comment from a position of knowledge about the impact of your mods, but that said, it’s hard for me to imagine any scenario where you are better off with 10W30 than 5W30. The W number gives you an indication of viscosity at startup temperature, while the upper number refers to viscosity at running temperature. All oil is too thick at startup temperature, but 5W30 is less bad than 10W30 in that regard. Actual viscosity numbers (as opposed to the general indicators of numbers like 5W30) are as follows. When hot at 212F, viscosity of both grades is about 12 centistokes. At 90F, 10W30 is about 90 centistokes while 5W30 is about 60. At 60F those numbers are about 170 versus 100. At 32F, the numbers are about 370 versus 190. Any time you are above about 100 centistokes, it is potentially a very high wear zone.
The only conditions under which you might be better off with a higher W number would be if the mods in your engine required a heavier oil at running temperature, such as 40 or 50 weight. Even there, a higher W number like 10W40 or 15W50 makes things worse at startup temperature. The advantage of a higher W number as you go higher in the plain number is that the wider the spread between the W number and plain number, the more VI improver additive you need. With a full synthetic, you can make a 25 spread (like 5W30 or 15W40) without much, if any VI improver. But higher spreads (like the 35 spread of 5W40 or 15W50) require VI improver. The disadvantage of VI improver is that it can degrade, and if it degrades, you lose viscosity on the high end, leaving your oil too thin at running temperature.
The only conditions under which you might be better off with a higher W number would be if the mods in your engine required a heavier oil at running temperature, such as 40 or 50 weight. Even there, a higher W number like 10W40 or 15W50 makes things worse at startup temperature. The advantage of a higher W number as you go higher in the plain number is that the wider the spread between the W number and plain number, the more VI improver additive you need. With a full synthetic, you can make a 25 spread (like 5W30 or 15W40) without much, if any VI improver. But higher spreads (like the 35 spread of 5W40 or 15W50) require VI improver. The disadvantage of VI improver is that it can degrade, and if it degrades, you lose viscosity on the high end, leaving your oil too thin at running temperature.
I wouldn’t worry much about occasional bursts up to 250-260F oil temp with 5W30. The guys who go to 40 or 50 weight are mostly track guys who run 250-260 all the time, with bursts even higher than that. And though it sounds counter-intuitive, 10W30 is actually thinner than 5W30 at 260F. That’s because the wider the spread between W and plain number, the shallower the slope of viscosity versus temperature. While they are both about 12 centistokes at 212F, by the time you’re up to 260F, 5W30 has only thinned out to about 9 centistokes, while 10W30 is down to 7. I start worrying around 7 or 8.
The problem with 15W50 is that if you drive on the street very much, starting from cold, you’re going to spend a fair amount of time over 100 centistokes during warmup. Quite a few people make 5W40, which is a decent compromise if you spend a lot of time at or over 260F and don’t want to worry about cold start issues. It does have a 35 spread, so uses some VI improver, but those additives are getting more stable, so aren’t as risky as they used to be. I’d be a bit nervous leaving it in too much over 5000 miles, but I’ve been retired 6 years so haven’t seen any VI improver stability data since then. Some of the European makes like BMW recommend 5W40 for normal change intervals, and you wouldn’t think they’d do that unless they had seen stability data to support it.
The problem with 15W50 is that if you drive on the street very much, starting from cold, you’re going to spend a fair amount of time over 100 centistokes during warmup. Quite a few people make 5W40, which is a decent compromise if you spend a lot of time at or over 260F and don’t want to worry about cold start issues. It does have a 35 spread, so uses some VI improver, but those additives are getting more stable, so aren’t as risky as they used to be. I’d be a bit nervous leaving it in too much over 5000 miles, but I’ve been retired 6 years so haven’t seen any VI improver stability data since then. Some of the European makes like BMW recommend 5W40 for normal change intervals, and you wouldn’t think they’d do that unless they had seen stability data to support it.
The car does see occasional cold street start ups in the winter months but not many. My garage is usually anywhere from 45-60*F in the winter with the oil temp matching during garage start up. But obviously if I'm parked outside somewhere during 30-35* temps, cold start up temps will be lower for awhile.
If I decide to get back on the track, I have no issue doing an oil change to something more beneficial for the extreme conditions. I don't see why I would need 15w50 unless I was at the track pushing the car. For normal usage, I want something more versatile during the various conditions I drive in. Which is ambient temperatures anywhere from 35-100*F consisting of cruising, highway bursts, and back road sprints. To me that sounds like I can go back to 5w30. Whether I decide on Mobil 1 or Amsoil is a separate discussion.
Another stupid question. Since I still have 6qts of Amsoil Zrod 10w30 left, what are your thoughts on mixing 3qts Amsoil 5w30 and 3qts Zrod 10w30 so as not to waste the oil? 7.5w30 with added ZDDP.....??
12-21-2016, 04:23 PM
#11
Drifting
Based on your 2 posts, I don't see any reason for me to use 10w30 then. I assumed the recommendation of the thicker oil was to help with the potential for higher heat and wear generated from the modified engine. However, based on your specs the 10w30 is actually offering less protection, not only at start up but also at operating temperatures and above. The added ZDDP from the Amsoil Zrod, part of the basis for the recommendation of that particular brand, seems to be the only helpful addition. And even then I wonder if it's necessary.
The car does see occasional cold street start ups in the winter months but not many. My garage is usually anywhere from 45-60*F in the winter with the oil temp matching during garage start up. But obviously if I'm parked outside somewhere during 30-35* temps, cold start up temps will be lower for awhile.
If I decide to get back on the track, I have no issue doing an oil change to something more beneficial for the extreme conditions. I don't see why I would need 15w50 unless I was at the track pushing the car. For normal usage, I want something more versatile during the various conditions I drive in. Which is ambient temperatures anywhere from 35-100*F consisting of cruising, highway bursts, and back road sprints. To me that sounds like I can go back to 5w30. Whether I decide on Mobil 1 or Amsoil is a separate discussion.
Another stupid question. Since I still have 6qts of Amsoil Zrod 10w30 left, what are your thoughts on mixing 3qts Amsoil 5w30 and 3qts Zrod 10w30 so as not to waste the oil? 7.5w30 with added ZDDP.....??
The car does see occasional cold street start ups in the winter months but not many. My garage is usually anywhere from 45-60*F in the winter with the oil temp matching during garage start up. But obviously if I'm parked outside somewhere during 30-35* temps, cold start up temps will be lower for awhile.
If I decide to get back on the track, I have no issue doing an oil change to something more beneficial for the extreme conditions. I don't see why I would need 15w50 unless I was at the track pushing the car. For normal usage, I want something more versatile during the various conditions I drive in. Which is ambient temperatures anywhere from 35-100*F consisting of cruising, highway bursts, and back road sprints. To me that sounds like I can go back to 5w30. Whether I decide on Mobil 1 or Amsoil is a separate discussion.
Another stupid question. Since I still have 6qts of Amsoil Zrod 10w30 left, what are your thoughts on mixing 3qts Amsoil 5w30 and 3qts Zrod 10w30 so as not to waste the oil? 7.5w30 with added ZDDP.....??
As long as you are using a full synthetic, I agree that there’s not a single advantage for 10W30 over 5W30, regardless of your climate, engine, or driving habits. Every single difference, without exception, favors 5W30. If you are using dino oil or a dino/synthetic blend, those oils require VI improver additive, and 10W30 has the advantage of needing less. So to the extent that you drive to long oil change intervals and are thus concerned about stability of VI improver, 10W30 does slightly lower the risk of viscosity loss for dino and dino/synthetic blends. Being able to make a 25 spread multi grade oil without having to use VI improver additive is the biggest single advantage of a full synthetic.
I don’t see any serious risk to mixing the oil. I’ve heard anecdotal stories about trouble from incompatible additives when mixing different brands of oil, but none have been sufficiently well documented to convince me that they weren’t caused by other factors and/or an overactive imagination. Oils and additives must meet mixing standards, so while you can’t categorically say it’s impossible, mixing issues would certainly be an extreme rarity, especially for two oils from the same oil company.
Last edited by LDB; 12-21-2016 at 05:33 PM. Reason: Fix spelling error
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mikeCsix (12-21-2016)
12-21-2016, 05:20 PM
#12
Melting Slicks
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Various zinc compounds were the first good EP additives, with EP being extreme pressure, as in gear teeth, flat tappets, etc. But if/when an engine starts burning a nontrivial amount of oil, zinc poisons your cats, so it is now regulated. Other, newer EP additives are essentially as good, and most engines including Vettes now have roller tappets, so I don’t see much need to search for high zinc content.
As long as you are using a full synthetic, I agree that there’s not a single advantage for 10W30 over 5W30, regardless of your climate, engine, or driving habits. Ever single difference, without exception, favors 5W30. If you are using dino oil or a dino/synthetic blend, those oils require VI improver additive, and 10W30 has the advantage of needing less. So to the extent that you drive to long oil change intervals and are thus concerned about stability of VI improver, 10W30 does slightly lower the risk of viscosity loss for dino and dino/synthetic blends. Being able to make a 25 spread multi grade oil without having to use VI improver additive is the biggest single advantage of a full synthetic.
I don’t see any serious risk to mixing the oil. I’ve heard anecdotal stories about trouble from incompatible additives when mixing different brands of oil, but none have been sufficiently well documented to convince me that they weren’t caused by other factors and/or an overactive imagination. Oils and additives must meet mixing standards, so while you can’t categorically say it’s impossible, mixing issues would certainly be an extreme rarity, especially for two oils from the same oil company.
As long as you are using a full synthetic, I agree that there’s not a single advantage for 10W30 over 5W30, regardless of your climate, engine, or driving habits. Ever single difference, without exception, favors 5W30. If you are using dino oil or a dino/synthetic blend, those oils require VI improver additive, and 10W30 has the advantage of needing less. So to the extent that you drive to long oil change intervals and are thus concerned about stability of VI improver, 10W30 does slightly lower the risk of viscosity loss for dino and dino/synthetic blends. Being able to make a 25 spread multi grade oil without having to use VI improver additive is the biggest single advantage of a full synthetic.
I don’t see any serious risk to mixing the oil. I’ve heard anecdotal stories about trouble from incompatible additives when mixing different brands of oil, but none have been sufficiently well documented to convince me that they weren’t caused by other factors and/or an overactive imagination. Oils and additives must meet mixing standards, so while you can’t categorically say it’s impossible, mixing issues would certainly be an extreme rarity, especially for two oils from the same oil company.
Sorry for the thread-jack Mr. Jones but when LDB gets going it's hard to keep from pressing him for more information. Hopefully some of it was helpful to you too.
